Filter Flow Rates

[zuulan]

Why is filter flow rates quoted and so important?

Isn't the most important thing how much area the filter media provides and hence how much bacteria you have in the filter?

 

[Cazgar]

You need good water flow through the filter to keep the good bacteria healthy & growing
About 10x the volume of your tank per hour is about right

 

[Tonyb111111]

You need good water flow through the filter to keep the good bacteria healthy & growing
About 10x the volume of your tank per hour is about right

Hi, can you help me out please as there are a lot of conflicting views on this. I've got a throughput of approx 5 x volume and I thought this good, now I'm confused again. Won't 10 x volume create a lot of flow in the tank that's some fish will get stressed with?

 

[soundteaser]

You need good water flow through the filter to keep the good bacteria healthy & growing
About 10x the volume of your tank per hour is about right

Hi, can you help me out please as there are a lot of conflicting views on this. I've got a throughput of approx 5 x volume and I thought this good, now I'm confused again. Won't 10 x volume create a lot of flow in the tank that's some fish will get stressed with?

Hi, as long as your filter can cope with the bio load you should be fine. You can have the most powerfull pump in the world but if it isn't pulling the water through enough filter material it is pointless. The filters on my tank do circulate 10x the water volume, but i do have malawi cichlids and they are messy buggers and it is quite heavily stocked. 5x water volume, in my opinion, is plenty for most modestly stocked tanks.

 

[m_attt]

You need good water flow through the filter to keep the good bacteria healthy & growing
About 10x the volume of your tank per hour is about right

Hi, can you help me out please as there are a lot of conflicting views on this. I've got a throughput of approx 5 x volume and I thought this good, now I'm confused again. Won't 10 x volume create a lot of flow in the tank that's some fish will get stressed with?

10x is more aimed at the planted tank i think, I have a nano 25litre with a 750litre eheim on it, around 30x turnover with no problems, and a 180litre tank with a 1750lph,1000lph and a 1250 koralia. fish dont seam to mind either.

 

[Cazgar]

All my tanks are planted, & I tend over filter, but as long as the filter copes with the bioload then you're good

 

[Tonyb111111]

Great answers guys, solves a problem i hav been contemplating. I am also planted but worry that i have dead spots, from what you guys say i have got plenty of scope to add more filtration or a powerhead to get rid of these. Any recommendations?

 

[soundteaser]

Great answers guys, solves a problem i hav been contemplating. I am also planted but worry that i have dead spots, from what you guys say i have got plenty of scope to add more filtration or a powerhead to get rid of these. Any recommendations?

I have a wave maker in my tank. This can be angled to provide good water movement where needed. My tank is not planted though, so i don't know if this would be suitable for you.

 

[AbbeysDad]

I don't understand how the 4x to 10x 'rule' ever got started. Logic dictates that good filtration is not about how much or how fast we move water through filter media, but how well we filter it. In fact, water moving much more slowly through very fine media will always be filtered better than water moving at high speeds. Also, unless handled properly, these fast flow filters can make fish life in the tank very difficult, nearly intolerable by some species. The filter on my 60g is less than 100gph (1.6x) and the water is crystal clear.

 

[FishFanatic04]

People use sponge filters, and there's no way the bubbles that rise form them create a 10x turnover. But they work great. But on my bigger tanks I use filters that are rated to a huge capacity over mine, but they are planted and you need the water movement.

 

[m_attt]

I don't understand how the 4x to 10x 'rule' ever got started. Logic dictates that good filtration is not about how much or how fast we move water through filter media, but how well we filter it. In fact, water moving much more slowly through very fine media will always be filtered better than water moving at high speeds. Also, unless handled properly, these fast flow filters can make fish life in the tank very difficult, nearly intolerable by some species. The filter on my 60g is less than 100gph (1.6x) and the water is crystal clear.

10x for a planted tank as it takes into the consideration that the lph the filter gives can be up to 50% less than actual and you want the co2 and nutrients pushed all around he tank, especially down too substrate level if growing a carpet plant. you can acheive good flow without churning the tank. rivers would have more flow.

 

[snazy]

In fact, water moving much more slowly through very fine media will always be filtered better than water moving at high speeds

I don't think this is true.

Just to elaborate:

The higher the flow, the more bits of ammonia reach the filter sponges in a certain period of time. In a cycled tank the ammount of ammonia in each ammount of water reaching the media of the filter may not be high enough so you need to keep feeding it by making sure more ammounts of water reach it at a certain period of time, thus getting a filter with a higher flow rate.
A slow water flow filter will eventually cycle the tank, but slower and I won't be too far wrong to say that this has been proven many times.
The bacteria needs to be "in thouch" with the ammonia in the water. It can't really get ammonia if the water is flowing around it and not through it which could be the case with some type of filters and slow water flow filters that don't hold the power to push through the media.
A filter rated 5x would probably be 2.5x in reallity once the sponges/media is added and I would not think this is enough for a tank.

Also, unless handled properly, these fast flow filters can make fish life in the tank very difficult, nearly intolerable by some species. The filter on my 60g is less than 100gph (1.6x) and the water is crystal

Not in my experience. One of my tanks filters 17 times the ammount of water an hour per manufacturers rates and I can't seem to see the fish blown around the place at all. It depends how you position the filter outlets. My fry tank is 15x the ammount of water an hour and they seem to be thriving. I have had guppy fry in it that some people say they don't like high flow rate and can cause problems. And the advantage is that if you happen to get overstocked for a while you never get water quality problems unlike a slower rate filters.